Various types of sugar cane harvesters have been devised in the last 30 years, and the improved technology resulting from these harvesters has reduced both the length of time and manpower required to harvest and truck sugar cane to a processing plant. With increasing environmental regulations, frequent reminders of poor seasonal weather harvesting conditions, and the continual insistence of cane processors to reduce the handling of dirt and waste products, improved equipment and techniques will be required to meet the demands of the 21st century for those people depending on the sugar cane industry for their livelihood.
Cane harvesting equipment in use today generally has high maintenance costs resulting from the overall harvester design. Some sugar cane which is cut by the harvester is left in the field, thereby reducing profits. When cane is not cut and piled in a manner substantially transverse to the cane rows, the cane pick-up operation performed by the loaders cannot effectively convey the cane onto trucks, so that more manpower is lost. Harvesting equipment must be continually regulated and the harvesting operation modified by a skilled operator, thereby draining the operator's energy and taxing his patience. Critical areas of the harvesting operation and cane movement through the harvester cannot be easily viewed by the operator. The overall design of the harvester results in a cloud of dust and debris which generally surrounds the harvester when in use, thereby creating a substantial nuisance and safety concerns for the harvester operator.
Early cane harvesters were designed for single row harvesting. Advantages of two or multiple row harvesters were well known, two row harvesters have been commonly used for decades. U.S. Pat. No. 3,090,183 disclosed a two row cane harvester which deposits the cut cane on a common cut cane row (heap row) between the two growing cane rows. Cut cane can also be moved laterally with cane pilers to drop the cane on an existing heap row. Cane travels through the harvesters with a hook chain which moves in channels defined by deflector bars. The basic mechanism described in this patent for moving cane through a harvester is still in use today.
Tricycle-type cane harvesters have been proposed, with the center or third wheel riding either within the furrow between the two rows of cane being cut or behind one of the front wheels. U.S. Pat. Nos. 4,308,281 and 4,473,130 disclose such three wheel harvesters. Cane harvesters of this type have inherent safety concerns involved in three wheel equipment, although tricycle-type cane harvesters are still widely used in the United States.
U.S. Pat. Nos. 4,165,596 and 4,232,775 also disclose four wheel, two row cane harvesters. The harvester according to the '596 patent is steered with differential drums and tackle for pivoting of front wheels, while the harvester of the '775 patent utilizes non-steerable front wheels and bellcranks connected to the steerable rear wheels for differential pivoting by the steering mechanism. In both embodiments, the cane moves from the front to the back of the machine in a pair of cane passageways generally in alignment with the two rows of growing cane, i.e., between the left side and right side wheels. One of the reasons for the relatively complex steering control mechanisms provided by these patents relates to the absence of a rear axle, which cut cane would otherwise have to pass up and over. Four wheel, two row cane harvesters have not been commercially accepted in the United States due to concerns associated with their overall design.
Another significant problem with prior art cane harvesters relates to the low velocity of the cut cane relative to tile earth when tile cane reaches the end of the first row conveyor system. The cane lacks uniform positioning when it reaches the end of the conveyor system, and when the pilers at the end of this system try to "trip" the cane across the rear of the machine, the cane frequently does not fall in a manner so that it is stacked substantially transverse to the cane rows. Harvester operators find it particularly difficult to trip the cane in the heap row transversely behind the machine, and accordingly a good amount of cane gets left in the field because it is not picked up by the loading equipment which relies on the assumption that the stacked cane will be generally transverse to the growing cane rows. Very significant problems are created when a loader operator, in an attempt to lift non-transverse cane, buries the loader piler into the soil and thus loads a good amount of mud and soil with the cut cane onto the transport, which is then hauled to the sugar mill and adversely affects refining operations. When harvesting the "fly" rows, existing cane harvesters also allow excess amounts of cane to be left in the field since the cane travels down relatively long conveyors and/or piler mechanisms positioned such that the cane travels in pathways substantially parallel to the growing rows on its way to being stacked in an existing cut cane row transverse to the growing rows. The greater distance cane must be moved from one point in order to be positioned properly for pick-up by the loaders, the greater the opportunity for the cane to drop out of the conveyor system and be left in the field. A still further problem with existing cane harvesters is that the operator cannot easily monitor either the tripping of cane when harvesting the center or heap rows (since the cane is tripped behind the machine), or the travel of cane in the carrier as it moves through the harvester to the pilers.
The design of prior cut cane harvesters also does not allow the harvester operator to easily monitor the height which the growing cane is cut off the ground. Accordingly, excess cane stubble is left in the field, particularly when cutting the first two rows of cane. The operator also cannot easily view the "downed" cane not picked up by the gathering assemblies and thus left in the field, and accordingly cannot reliably alter the operation of the front end gathering assemblies. The problem is in part dependant upon the overall design of the cane harvesters which, as previously noted, also results in large quantities of dust and debris following the harvester through the field. The successful operation of a cane harvester requires a significant amount of training and expertise, and even with this training, use of harvesting equipment is highly taxing upon the operator. One of the difficulties encountered by a harvester operator relates to the operator continually adjusting the speed of the main carrier mechanism through the harvester and the position of the base or foot of the cut cane in an attempt to control the cane as it is tripped across the rows.
These and further disadvantages of the prior art are overcome by the present invention, and an improved cane harvester is hereinafter disclosed.